Non-Hodgkin lymphoma (NHL) is the sixth most common malignancy in the US. By improving understanding of the causes of NHL in the general population, we will identify the individuals at highest risk of developing NHL as well as elucidate mechanisms of lymphomagenesis. Additionally, NHL is one of the most common malignancies occurring among immunosuppressed individuals, including those with HIV/AIDS and those receiving iatrogenic immunosuppression to prevent graft rejection following transplantation. Because individuals with HIV are living longer with improved immune function, this research will identify HIV-positive individuals who are at highest risk for developing NHL based on other etiologic factors.1. We completed analysis of the main case-control study and published approximately 80 reports in peer-reviewed journals. 2. To conduct a GWAS and to study genetic polymorphisms with more power, we are pooling data within the International Lymphoma Epidemiology Consortium (InterLymph). 3. We continued to collaborate with InterLymph on other analyses as well, including a broad range of environmental, medical history, and lifestyle factors.4. Through this collaborative research, we demonstrated that the patterns of risk vary according to the subtype of lymphoma. In particular, we showed that various immune-related medical conditions (e.g., autoimmune diseases, hepatitis C viral infection) are most closely associated with certain NHL subtypes. These subtypes are the same as those that are most strongly elevated among individuals with HIV/AIDS and following solid organ transplantation. 5. We combined environmental data from other sources with study data to continue to investigate environmental risks. This work is ongoing.